Claims
- 1. A drafting apparatus having an apron zone for drafting a sliver in a yarn spinning machine comprising:
- at least one apron drafting mechanism comprising a pair of upper and lower inlet rollers forming a rearward apron nipping area, an upper apron and a lower apron, a spring loaded upper apron cradle mechanism having a forward nose for engaging the upper apron, a guide having an upper surface and a forward nose for engaging the lower apron and a pair of upper and lower sliver delivery rollers;
- the upper apron traveling around the upper inlet roller and around said forward nose of said cradle mechanism, and the lower apron traveling around the lower inlet roller and around said forward nose of said guide;
- said guide having at least one step-like recess in its upper surface upwardly facing the lower apron, said step-like recess having a rearward edge and said spring loaded cradle mechanism urging the upper apron downwardly into pressing engagement with said lower apron;
- the pressingly engaged aprons forming a sliver path therebetween which is substantially S-shaped along a substantial length of the path between the inlet rollers and the delivery rollers.
- 2. The drafting apparatus of claim 1 wherein said forward nose of said cradle mechanism extends forwardly beyond said forward nose of said guide, said spring loaded cradle mechanism urging said upper apron downwardly over said forward nose of said guide such that said first substantial angular deflection takes place over said forward nose of said guide and said second angular deflection takes place around said forward nose of said cradle mechanism.
- 3. The drafting apparatus of claim 1 wherein said forward nose of said cradle mechanism extends forwardly beyond said forward nose of said guide, the spring loaded cradle mechanism urging the upper apron downwardly into engagement with the lower apron the sliver being directed over the nose of the cradle mechanism toward the lower delivery roller.
- 4. The drafting apparatus of claim 1 wherein said forward nose of said guide extends forwardly beyond said forward nose of said cradle mechanism, the spring loaded cradle mechanism urging the upper apron extending around said forward nose of said cradle mechanism into said recess of said guide, said first substantial angular deflection taking place around said forward nose of said cradle mechanism within said recess and said second angular deflection taking place over said forward nose of said guide.
- 5. The drafting apparatus of claim 4 wherein said sliver is directed over said forward nose of said guide toward the upper delivery roller.
- 6. The drafting apparatus of claim 1 wherein said guide is mounted under the lower apron and has an upper surface extending back to front over which the lower apron extends and is supported in contact with the lower apron, the recess being disposed in the upper surface intermediate its back to front extension.
- 7. The drafting apparatus of claim 1 wherein said forward nose of said guide and of said cradle mechanism are curved for readily enabling the aprons to slidably travel therearound.
- 8. The drafting apparatus of claim 1 wherein said forward nose of said cradle mechanism extends forwardly beyond said forward nose of said guide such that said forward nose of said cradle mechanism is disposed closely adjacent to the lower delivery roller preventing air from being drawn into the nip of the delivery rollers.
- 9. The drafting apparatus of claim 1 wherein said forward nose of said guide extends forwardly of said forward nose of said cradle mechanism such that said forward nose of said guide is disposed closely adjacent to the upper delivery roller preventing air from being drawn into the nip of the delivery rollers.
- 10. The drafting apparatus of claim 1 wherein the rearward apron nipping area and a position at which said first angular deflection of said sliver occurs are spaced apart by a distance less than or equal to a mean staple length of the sliver fibers.
- 11. In a drafting apparatus for drafting a sliver in a yarn spinning machine, said drafting apparatus comprising upper and lower inlet rollers, upper and lower apron belts, upper and lower apron belt guides, and upper and lower outlet rollers, wherein said upper apron belt passes around said upper inlet roller and said upper apron belt guide, and wherein said lower apron belt passes around said lower inlet roller-and said lower apron belt guide and cooperates with said upper apron belt to define an inlet nipping area between said belts for nipping the fiber sliver as it passes between said upper and lower inlet rollers while being sandwiched between said upper and lower apron belts, said sliver being nipped in said nipping area and being subsequently directed by said belts to a nip formed between said upper and lower outlet rollers, and wherein a nose region of one of said upper and lower apron belt guides, around which one of the apron belts is deflected extends closer up to the inlet and outlet rollers than the other nose region of the other one of said upper and lower apron belt guides, around which the other apron belt is deflected, the improvement wherein said upper and lower apron belt guides have curved apron belt engaging surfaces over at least substantially the full length of contact with the respective apron belts as the belts pass from said upper and lower inlet rollers towards said nose region, and wherein the upper and lower apron belt guides cooperate to define a generally S-shaped path for said sliver from said inlet nipping area to the nip of said upper and lower outlet rollers, both of said apron belts lying substantially parallel to one another over at least the first curve of said S-shaped path following said nipping area, said sliver being guided thereafter by at least one apron belt.
- 12. A drafting apparatus in accordance with claim 11 wherein said lower guide has a convexly curved surface extending up to its nose region and forming a first portion of said S-shaped path around which said lower apron belt is guided and wherein said upper guide has a convexly curved surface extending up to its nose region defining a second part of said S-shaped path around which said upper apron belt passes, with said first and second parts of said S-shaped path merging into each other via a smooth tangential transition, and wherein said nose region of said upper apron belt extends furthest towards said nip formed between said upper and lower outlet rollers.
- 13. A drafting apparatus in accordance with claim 11 wherein said lower guide has a curved generally S-shaped guide surface for said lower apron belt, said S-shaped guide surface extending substantially up to said nose region of said lower guide and wherein said upper guide has a convexly curved guide surface extending up to its nose region, with said convexly curved guide surface of said upper apron belt guide being disposed adjacent to and conforming in shape to the curve of the S-shaped surface of said lower guide adjacent said upper and lower outlet rollers.
- 14. A drafting apparatus in accordance with claim 13 wherein said nose-shaped region of said upper apron belt guide extends in a smooth curve into said S-shaped guide surface of said lower apron belt guide and said fiber sliver lying on said lower apron belt is subjected to a further deflection around a top surface of said nose-shaped region of said lower guide immediately prior to entry into said nip between said inlet and outlet rollers.
- 15. A drafting apparatus in accordance with claim 11 wherein said fiber sliver is guided by continuously curved surfaces over substantially the full extent of its path from said nipping area to said nip.
- 16. A drafting apparatus in accordance with claim 12 wherein an angle .alpha. formed between a first tangent to the upper and lower inlet rollers in said nipping area and a tangent to said convexly curved surface of said lower guide at a transition of said fiber sliver from said convexly curved surface of said lower guide to said convexly curved surface of said upper guide lies in the range from 20.degree. to 50.degree..
- 17. A drafting apparatus in accordance with claim 16 wherein said angle .alpha. amounts to 40.degree..
- 18. A drafting apparatus in accordance with claim 12 wherein an angle .beta. between a tangent to said convexly curved surface of said lower guide at a point of transition of said sliver from said convexly curved surface of said lower guide to said convexly curved surface of said upper guide and a tangent to said curved surface of said upper guide at a point of separation of said fiber sliver from said curved surface of said upper guide adjacent to said nip, lies in the range from 10.degree. to 30.degree..
- 19. A drafting apparatus in accordance to claim 18 wherein said angle .beta. amounts to 20.degree..
- 20. A drafting apparatus in accordance with claim 12 wherein an angle .gamma. tangent to said convexly curved surface of said upper guide at a point of separation of said fiber sliver from said upper guide adjacent said nip and a tangent to said upper and lower outlet rollers at said nip, lies in the range from 5.degree. to 15.degree..
- 21. A drafting apparatus in accordance to claim 20 wherein said angle .gamma. amounts to 10.degree..
- 22. A drafting apparatus in accordance with claim 13 wherein an angle .delta. between a tangent to said inlet and outlet rollers at said nipping area and a tangent to said S-shaped guide surface at a transition point where said sliver is guided around said convexly curved surface of said upper guide lies in the range from 15.degree. to 40.degree..
- 23. A drafting apparatus in accordance with claim 22 wherein said angle .delta. amounts to 30.degree..
- 24. A drafting apparatus in accordance with claim 13 wherein an angle .epsilon. between a tangent to said S-shaped guide surface of said lower guide at a transition point where said sliver is guided around said convexly curved surface of said upper guide and a tangent to said curved surface of said upper guide at a point of separation of said fiber sliver therefrom adjacent to said nip of said upper and lower outlet roller pair lies in the range from 5.degree. to 20.degree..
- 25. A drafting apparatus in accordance with claim 24 wherein said angle .epsilon. amounts to 15.degree..
- 26. A drafting apparatus in accordance with claim 13 wherein an angle .xi. between a tangent to said curved guide surface of said upper guide at a point of separation of said sliver from said curved surface of said upper guide adjacent to said nip of said upper and lower outlet rollers and a tangent to said S-shaped curved guide surface of said lower guide at said nose region at a point of separation of said sliver from said lower guide adjacent said nip lies in the range from 5.degree. to 20.degree..
- 27. A drafting apparatus in accordance with claim 26 wherein said angle .xi. amounts to 15.degree..
- 28. A drafting apparatus in accordance with claim 12 wherein an angle .pi. between a tangent to said S-shaped guide surface of said lower guide at a point of separation of said sliver from said lower guide adjacent to said nip between said upper and lower outlet rollers at said nip lies in the range from 5.degree. to 15.degree..
- 29. A drafting apparatus in accordance with claim 28 wherein and angle .pi. amounts to 10.degree..
- 30. A drafting apparatus in accordance with claim 12 wherein said convexly curved guide surface has a radius of curvature, at least at a central portion thereof, lying in the range from 15 to 50 mm.
- 31. A drafting apparatus in accordance with claim 30 wherein said radius amounts to 25 mm.
- 32. A drafting apparatus in accordance with claim 12 wherein said curved guide surface of said upper guide has a radius of curvature at a position where said sliver separates therefrom in the range from 2 to 5 mm.
- 33. A drafting apparatus in accordance with claim 32 wherein said radius amounts to 30 mm.
- 34. A drafting apparatus in accordance with claim 13 wherein said S-shaped guide surface of said lower guide has a radius of curvature over at least a portion of a first curve of said S at a position between said upper and lower inlet rollers and a point of transition to a second curved portion of said S-shaped guide surface in the range from 30 to 40 mm.
- 35. A drafting apparatus in accordance with claim 34 wherein said radius amounts to 20 mm.
- 36. A drafting apparatus in accordance with claim 13 wherein said convexly curved surface of said upper guide has a radius of curvature at a position confronting said S-shaped guide surface of said lower guide in the range from 2 to 5 mm.
- 37. A drafting apparatus in accordance with claim 34 wherein said radius amounts to 3 mm.
- 38. A drafting apparatus in accordance with claim 13 wherein said lower guide has a radius of curvature at said nose region at a point of separation of said sliver from said lower guide lying in the range from 2 to 5 mm.
- 39. A drafting apparatus in accordance with claim 38 wherein said radius amounts to 3 mm.
- 40. A drafting apparatus in accordance with claim 11 wherein resilient bias means is provided for resiliently biasing at least one of said upper and lower guides towards the other one of said upper and lower guides.
- 41. A drafting apparatus in accordance with claim 12 wherein said nose region of said upper guide is disposed sufficiently close to said upper and lower outlet rollers that said upper apron belt passing around said nose region is spaced from said upper and lower outlet rollers by a clearance of less than 2 mm.
- 42. A drafting apparatus in accordance with claim 13 wherein said nose region of said lower guide is disposed sufficiently close to said upper and lower outlet rollers that said lower apron belt passing around said nose region is spaced from said upper and lower outlet rollers by a clearance of less than 2 mm.
- 43. A drafting apparatus in accordance with claim 12 wherein a distance from a point at which said fiber sliver separates from said lower apron belt to said nip amounts to less than the staple length of fibers of said sliver.
- 44. A drafting apparatus in accordance with claim 43 wherein said distance amounts to less the 75% of said staple length.
- 45. A drafting apparatus in accordance with claim 13 wherein a distance from a point at which said sliver separates from said upper apron belt to said nip amounts to less than a stable length of said fibers.
- 46. A drafting apparatus in accordance with claim 45 wherein said distance amounts to less than 75% of said staple length.
- 47. A drafting apparatus having an apron zone for drafting a sliver in a yarn spinning machine comprising:
- at least one apron drafting mechanism comprising a pair of upper and lower apron inlet rollers forming a rearward apron nipping area, an upper apron and a lower apron, a spring loaded upper apron cradle mechanism having a forward nose for engaging the upper apron, a guide having an upper surface and a forward nose for engaging the lower apron and a pair of upper and lower sliver delivery rollers;
- the upper apron travelling around the upper inlet roller and around said forward nose of said cradle mechanism, and the lower apron traveling around the lower inlet roller and around said forward nose of said guide;
- said spring loaded cradle mechanism urging the upper apron downwardly into pressing engagement with said lower apron, the pressingly engaged aprons forming a sliver path therebetween which is substantially S-shaped along a substantial length of the path between the inlet rollers and the delivery rollers.
- 48. A drafting apparatus having an apron zone for drafting a sliver in a yarn spinning machine comprising:
- an apron drafting mechanism comprising a pair of upper and lower apron inlet rollers forming a first nipping area, an upper and a lower apron, an upper guide having a forward nose for engaging the upper apron, a lower guide having an upper surface and a forward nose for engaging the lower apron and a pair of upper and lower sliver delivery rollers forming a second nipping area;
- the upper apron travelling around the upper inlet roller and the forward nose of the upper guide, and the lower apron travelling around the lower inlet roller, over the upper surface and around the forward nose of the lower guide;
- the upper and lower aprons being resiliently pressed against each other such that a sliver may be delivered between the first and second nipping areas with the sliver sandwiched under the pressure between the aprons;
- the upper and lower guides engaging the pressed together upper and lower aprons such that the sliver, during the course of travel between the first and second nipping areas, is substantially deflected in at least one upward direction out of the straight line path between the nipping areas and is also substantially deflected in at least one downward direction out of the straight line path between the nipping areas such that the sliver path between the first and second nipping areas is substantially S-shaped.
- 49. The drafting apparatus of claim 48 wherein the upper and lower guides engage the upper and lower aprons such that the sliver is deflected in a third direction out of the straight line path between the nipping areas during the course of travel of the sliver between the nipping areas.
- 50. The drafting apparatus of claim 49 wherein the sliver travels between the first and second nipping areas in a path which is at least partially S-shaped.
- 51. The drafting apparatus of claim 48 wherein the sliver travels between the first and second nipping areas in a path which is at least partially S-shaped.
Priority Claims (1)
Number |
Date |
Country |
Kind |
01175/90 |
Apr 1990 |
CHX |
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Parent Case Info
The present application is a continuation in part of U.S. application Ser. No. 07/681,047 filed Apr. 5, 1991 for DRAFTING ARRANGEMENT WITH AT LEAST ONE APRON DRAFTING ZONE which is entitled to priority of Swiss Application No. 01 175/90-3 filed Apr. 6, 1990.
US Referenced Citations (5)
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
681047 |
Apr 1991 |
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